(1) Field of the Invention
The present invention relates to a polyimide film having a high tensile strength and high elastic modulus and also having a very high heat resistance.
(2) Description of the Prior Art
Among organic polymers a wholly aromatic polyimides have the highest heat resistance, and these polymers have already been practically used in the form of a film or molded article in which this characteristic is effectively utilized. However, the tensile properties of these polymers are at very common levels and the strength and elastic modulus are not high. Recently, there has arisen a demand for a film having a high elastic modulus and a high heat resistance, in combination, in the field of base films for magnetic recording tapes.